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West Pacific/2015/11W/Archive/11
Public advisory TROPICAL STORM NANGKA PUBLIC ADVISORY NUMBER 11 WIKI-HURRICANES FORECASTING CENTER 12:00 PM JST SUN JUL 06 2015 ...NANGKA DEVELOPING A RAGGED EYE... SUMMARY OF 12:00 PM JST...03:00 UTC...INFORMATION ------------------------------------------------------------------- LOCATION...11.8, 159.3E CENTER POSITION CONFIDENCE: FAIR ... ± 35 MI... 60 KM ABOUT 340 MI...550 KM NE OF PALIKIR, MICRONESIA MAXIMUM SUSTAINED WINDS...60 KT...70 MPH...110 KM/H MINIMUM BAROMETRIC PRESSURE...984 MB...29.06 INCHES PRESENT MOVEMENT...NNE AT 15 KT...16 MPH...25 KM/H DISCUSSION AND 48-HOUR OUTLOOK --------------------------------------------- At 12:00 pm JST, the center of Tropical Storm Nangka was situated near 11.8N, 159.3E, or about 340 miles (550 kilometers) north-northeast of Palikir, Micronesia. Maximum sustained winds were 60 knots (70 mph, 110 km/h), with higher gusts. The minimum barometric pressure was 984 millibars (hPa; 29.06 inHg), and the cyclone was tracking west-northwest at 15 knots (16 mph, 25 km/h). Environmental conditions over the next two days are expected to allow for steady strengthening as Nangka tracks west-northwestward. NEXT ADVISORY ------------------- Next complete advisory at 12:00 am JST. $$ Forecaster TheAustinMan Discussion TROPICAL STORM NANGKA PUBLIC DISCUSSION NUMBER 11 WIKI-HURRICANES FORECASTING CENTER 12:00 PM JST SUN JUL 06 2015 Nangka has continued to organize throughout the morning hours, which continued deep convection across the eastern semicircle and attempts at rainband development to the southwest on and arc eastward to the northeast. Although the low-level circulation for Nangka has been displaced west of the cloud cover for most of the storm's lifetime, additional convection wrapping around to the west of the circulation has resulted in the development of a large, ragged eye, which indicates that Nangka is strengthening. Long streams of cirrus outflow extend equatorward and are also spiralling off to the northeast of the cyclone, indicating that the storm is well ventilated. The latest CIMSS-ADT estimate suggested T3.4/53kt, but SATCON indicates a stronger 60kt system. Given the development of the ragged eye and continued deep convection, the intensity for this advisory has been raised upwards to 60 knot, making Nangka a high-end tropical storm. Nangka has sped up some towards the west-northwest, but generally speaking its motion is expected to be of moderate speed towards the west-northwest as it rounds the periphery of a 594dm subtropical high. After around two days Nangka is expected to take a course more northwesterly, but still towards the west-northwest, as an advancing trough creates a weakness and the ridge, pushing the ridge further east. This should bring Nangka near or even over the northern Mariana Islands in roughly three or four days. Afterwards, the advancing trough is expected to force Nangka in a different direction, most likely towards the north, though the specifics of this interaction is rather unclear at this time and diverges between the models. For the most part, the WHFC track remains largely the same and follows the general model consensus. Conditions are expected to be generally favorable for steady strengthening as Nangka moves towards the northern Mariana Islands. Sea surface temperatures are expected to remain warm during the next five days, and oceanic heat content remains favorable, with maximum potential intensity values of around 140 knots. Currently Nangka lies in 15kt shear and should shortly be entering some increasing wind shear, which may hamper intensification a bit, depending on how badly the low-level circulation separates from the main convective core. COAMPS indicates promptly decreasing shear, which at some point is anticipated, but due to the analyzed shear immediately ahead of Nangka, it is safe to say that this decrease in shear will likely be delayed. However, conditions further out remain favorable, and thus the short term intensity forecast for Nangka has been slightly scaled back, but accelerates in the longer term. INIT 06/0300Z 11.8N 159.3E 60 KT 70 MPH 12H 06/1200Z 11.6N, 161.5W 65 KT 75 MPH 24H 07/0000Z 13.3N 155.6E 70 KT 80 MPH 36H 07/1200Z 14.4N 153.3E 75 KT 85 MPH 48H 08/0000Z 15.5N 151.1E 80 KT 90 MPH 72H 09/0000Z 17.3N 148.5W 95 KT 110 MPH ... NEAR NORTHERN MARIANA ISLANDS 96H 10/0000Z 19.9N 145.0E 110 KT 125 MPH ... NEAR NORTHERN MARIANA ISLANDS 120H 11/0000Z 22.4N 141.9E 120 KT 140 MPH $$ Forecaster TheAustinMan